JohnnyJetTech

The purpose of the Tilt Relay is to use smaller gauge wires to the headlight switch, and therefore less amperage on switch contacts. If the DRL relay works correctly in the '91, that proves the relay is NOT sticking/defective. If the '94 uses the same p/n relay, then it is being energized by the '94 wiring. Verify the relay is correct for the '94, and that the terminal locations match the diagram. I can't read the diagram on my small screen. My guess (I don't warranty guess-work troubleshooting) is the switch is designed to supply a ground for the tilt relay, which then closes and powers the headlights. If this is verified by the diagram, I'd check for a "Grounded" ground wire from the relay.

Hi everybody, my buddy just bought a 1978 Mack R model Dump Truck. I help him with electrical work. I've already replaced the solenoid for the switched bus bar, and rebuilt the heater switch. I joined to learn from all the collected knowledge here.